Tastes and flavor of beverages and foods have a major influence on decrease or diminution of appetite, and therefore flavor is considered to be an element of dietary habit that is as important as nutrition. The fragrances imparted to cosmetics and toiletries such as soaps and shampoos are important elements for masking base odors and providing a pleasant sensation to the user or surrounding persons.
However, it is well known that the flavors and fragrance components in foods and beverages or in cosmetics are generally unstable and deteriorate by the effects of oxygen, light and heat, resulting in loss of the original flavors or fragrances, or generation of off-flavors or off-odors (deterioration odors), during various stages of production, distribution and storage.
Citral has a lemon-like fragrance and flavor, and is an important component used to impart a fresh, citrus sensation to products such as foods and beverages or cosmetics. Under acidic conditions, citral is known to undergo reactions such as cyclization, oxidation, hydration and isomerization, producing various off-flavor components [Peter Schieberle and Werner Grosch; J. Agric. Food Chem., Vol. 36, 797-800 (1988)].
Among the off-flavor components, p-methylacetophenone and p-cresol exhibit particularly strong deterioration odors and notably impair product quality.
Past efforts at inhibiting such deterioration of flavor and fragrance have included addition of various antioxidants or photodegradation inhibitors such as ascorbic acid (see Non-patent document 1).
Methods of adding plant extracts such as rosmarinic acid, perilla or peppermint to retard deterioration of citral have been disclosed (see Patent documents 1-11).
Methods of inhibiting deterioration of citral by addition of tea-derived components such as catechins and theaflavins have also been reported (see Patent documents 12-14).
However, deterioration of the flavors and fragrances of foods and beverages or cosmetics occurs not only as a result of the changes in the flavor and fragrance components themselves induced by oxygen, light and heat, but also due to a combination of numerous contributing reactions including oxidation, decomposition, isomerization and polymerization of different components such as fats and oils, proteins, saccharides, amino acids and organic acids in the foods and beverages or cosmetics. The inhibiting effect against deterioration has therefore often been inadequate with prior art methods, such that more powerful methods of retarding deterioration have been desired.    [Non-patent document 1] “Patent Office Report: Collection of Well-Known Prior Arts (Flavoring Agents), Section 1”, Jan. 29, 1999 p 141-147    [Patent document 1] Japanese Patent Public Inspection No. 2002-507887    [Patent document 2] Japanese Unexamined Patent Publication HEI No. 11-137224    [Patent document 3] Japanese Unexamined Patent Publication HEI No. 11-169148    [Patent document 4] Japanese Unexamined Patent Publication No. 2001-346558    [Patent document 5] Japanese Unexamined Patent Publication No. 2002-244    [Patent document 6] Japanese Unexamined Patent Publication No. 2002-180081    [Patent document 7] Japanese Unexamined Patent Publication No. 2002-255778    [Patent document 8] Japanese Unexamined Patent Publication No. 2002-330741    [Patent document 9] Japanese Unexamined Patent Publication No. 2002-338990    [Patent document 10] Japanese Unexamined Patent Publication No. 2003-82384    [Patent document 11] Japanese Unexamined Patent Publication No. 2003-79335    [Patent document 12] Japanese Unexamined Patent Publication No. 2003-96486    [Patent document 13] Japanese Unexamined Patent Publication HEI No. 9-227456    [Patent document 14] Japanese Unexamined Patent Publication No. 2005-171116